The most audible factor would be linear decay (..beyond freq. linearity and power response).
In the decay plots the B&C is considerably better:
B&C:
http://s139.photobucket.com/albums/q288/augerpro/BC 8NDL51/?action=view¤t=CSD_35dBrange.jpg
18 Sound:
http://s139.photobucket.com/albums/...NMB420/?action=view¤t=CSD_35dBrange.jpg
The resonance is only a concern with regard to:
1. non-linear behavior, which as Dennis has posted is good (..and also linear behavior - which is also decent as seen in the decay plots),
2. getting the correct values for the crossover and an impedance that doesn't "shift"/change much while in normal operation.
BTW, a big thanks to augerpro for his measurements of these drivers!
In the decay plots the B&C is considerably better:
B&C:
http://s139.photobucket.com/albums/q288/augerpro/BC 8NDL51/?action=view¤t=CSD_35dBrange.jpg
18 Sound:
http://s139.photobucket.com/albums/...NMB420/?action=view¤t=CSD_35dBrange.jpg
The resonance is only a concern with regard to:
1. non-linear behavior, which as Dennis has posted is good (..and also linear behavior - which is also decent as seen in the decay plots),
2. getting the correct values for the crossover and an impedance that doesn't "shift"/change much while in normal operation.
BTW, a big thanks to augerpro for his measurements of these drivers!
catapult said:Resonance-caused distortion peaks also don't appear to be a problem with the B&C.
Good post. It's clear the differences between the two are quite negligable for midrange duty. The added efficiency and lower cost of the B&C makes it a no brainer for me. For a woofer instead, the 18sound makes a bit more sense. Either of these on a wide baffle with an OB 15" Pro woofer would make for an excellent system. The SB acoustics SB29 tweeter WG modded would be a nice compliment. Sensitivity would be high across the board at around 93db. There's plenty of affordable 15's with 98+db efficiency to choose from. A slight horn loading of the Mid would be an interesting feature which would help to align the centers. You could cross lower with this approach as well. Good God..i've outlined an entire project.....sorry for rambling!
Defo said:
Seems like you have answered your own questions.
For sealed boxes (and no high-pass filter):
http://www.baudline.com/erik/bass/xmaxer.html
none of those paper 6-8 in cones are usable as midranges
around 1k most of them have large hump in FR, which is a one huge, sometimes smooth looking, resonance.
which creates screaming sound.
I don't know about larger woofers used as midranges.
since less than 1mm of xmax is used, maybe there is not enough force to excite paper resonance
around 1k most of them have large hump in FR, which is a one huge, sometimes smooth looking, resonance.
which creates screaming sound.
I don't know about larger woofers used as midranges.
since less than 1mm of xmax is used, maybe there is not enough force to excite paper resonance
Defo said:
Just partcily
If we're still talking the same midrange duty to 2.5khz, i'd look at the FR of both before doing so. Things start to get a bit rough above 1.5k for both. The 8NDL51 would make a great high power two way crossed around 2khz LR2 with maybe a WG mounted dome. I have four of them with plans for a TMM at some point.
MisterTwister said:none of those paper 6-8 in cones are usable as midranges
around 1k most of them have large hump in FR, which is a one huge, sometimes smooth looking, resonance.
which creates screaming sound.
If what you elude to is a resonance, it would show up in the impedance plot.....which it doesn't.
If you meant to say 'beaming' instead of 'screaming' then yes..i agree there's a potential which the 18Sound may have addressed in the odd cone shape.
1k bump is hard to see, but it is still visible on Zaph's test page. I don't know why he smooths impedance and zooms out of it so much.
no, I meant "screaming". From my personal experience those thin paper cones are not usable for 1K+ range, including seas CA series, usher and scanspeak revelator.
no, I meant "screaming". From my personal experience those thin paper cones are not usable for 1K+ range, including seas CA series, usher and scanspeak revelator.
Why is thin paper cone not OK for mid-high? It's so frustrating when I read this
Then, what's the better solution for 1kHz and up? Compression driver + WG/horn ? Or something else?
I'm also very curious about the driver's size. I always have a feeling that 8" is a very popular size for wide-rangers, but quite the opposite for a pure midrange. When discussing midrange, I found there're 2 camps, one is smaller sizes -- 4 or 5", 6.5" is the largest acceptable, these are mostly home use hi-fi style drivers. While the other is bigger sizes, 10~15", and they are mostly pro sound style drivers. Among them, it seems 8" is abandoned, or avoided. This also reflects in product catalogs of various manufacturers.
How come?
Many people say <a good wide-ranger could be an excellent pure midrange>. And I tend to agree. But why the most popular size of wide-rangers is avoided when designing a pure midrange?
OK, maybe I'm somewhat arbitrary about this, but it should be fair to say 8" pure midrange is not so popular as 8" wideranger, thus the choices are relatively limited.
Then, what's the better solution for 1kHz and up? Compression driver + WG/horn ? Or something else?
I'm also very curious about the driver's size. I always have a feeling that 8" is a very popular size for wide-rangers, but quite the opposite for a pure midrange. When discussing midrange, I found there're 2 camps, one is smaller sizes -- 4 or 5", 6.5" is the largest acceptable, these are mostly home use hi-fi style drivers. While the other is bigger sizes, 10~15", and they are mostly pro sound style drivers. Among them, it seems 8" is abandoned, or avoided. This also reflects in product catalogs of various manufacturers.
How come?
Many people say <a good wide-ranger could be an excellent pure midrange>. And I tend to agree. But why the most popular size of wide-rangers is avoided when designing a pure midrange?
OK, maybe I'm somewhat arbitrary about this, but it should be fair to say 8" pure midrange is not so popular as 8" wideranger, thus the choices are relatively limited.
I think strong and well damped cones is the reason pro woofers are preferred for midrange use.
I've seen only one 6in paper driver, that I'd use for midrange.
I pulled it out of altec lansing sub
http://img403.imageshack.us/img403/286/alteca4468.jpg
cone is so thick and stiff, you can't bend it's edges.
I think this one must be really good also
http://www.madisound.com/catalog/product_info.php?products_id=8642
I've seen only one 6in paper driver, that I'd use for midrange.
I pulled it out of altec lansing sub
http://img403.imageshack.us/img403/286/alteca4468.jpg
cone is so thick and stiff, you can't bend it's edges.
I think this one must be really good also
http://www.madisound.com/catalog/product_info.php?products_id=8642
StigErik said:
Hello Erik ,
What i will say is this,
On Single sinusoidal waveform the measurement flatters to deceive with such a large surface area Driver. THD rises exponentially when feed with multiple waveform as in real music .
Also if for PA sound reinforcement that setup ( JBL) is more acceptable as the goals are completely different than that for Hi-fi , sound reproduction ......
regards,
MisterTwister said:
Using ARTA Steps and measuring a wide array of ten to 21 inch drivers pretty much confirms what "John_E_Janowitz" said earlier. A good high efficiency 12 or 15 is low distortion for the 100 to 1000 cycle decade. Also when you take account the low distortion high output capability and narrowing radiation it makes perfect sense to me to use one.
I like a twelve crossed at 1200 cycles to an 18 Sound horn.
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